Salt Lake City, Utah -- The ghosts of dinosaurs still wander the vast openspaces of the American Southwest, as suggested by their fossilized footprints, aPenn State paleontologist said today (Oct. 20) at the annual meeting of theGeological Society of America in Salt Lake City.
The elusive, giant beasts left a legacy 180 million years ago that cannow be seen at Pipe Spring National Monument near Moccasin, Ariz., along theUtah border. This monument preserves an historic fort and structures built byMormon pioneers during their settlement of the Southwest.
"At many localities, dinosaur footprints are mentioned in theliterature, but no one has documented them," said Dr. Roger J. Cuffey, professorof paleontology in Penn State's College of Earth and Mineral Sciences. "Thereare more than 25 mentions of dinosaur prints in rocks of the same age as PipeSpring, but only 7 or 8 have been adequately published."
Cuffey wasn't looking for new footprints at Pipe Spring. He was tryingto take a photograph of a dinosaur footprint reported there for hisundergraduate class in dinosaurs.
"In a 1988 booklet on where to go to see dinosaurs, Professor WilliamLee Stokes mentioned a natural cast of a dinosaur footprint at the visitor'scenter at Pipe Spring National Monument," said Cuffey. "The people at the parkthought the cast was in storage, but asked me if I'd seen the dinosaurfootprints in place on the mesa."
The footprints are on a mesa behind the ranch buildings, and are from athree-toed beast. They were only discovered in the mid-1990s. Two of thefootprints are nearly side by side about 1.5 feet apart and the other footprintis 8 feet in front.
"I thought that these prints should be documented," said Cuffey. "Andthat they would be a good undergraduate project."
Two undergraduates, Maria Di Nardo and Bryan Herzing, who have bothsince graduated, worked on identifying and documenting the footprints for seniortheses. Their literature search turned up a sizeable number of documented printsfrom the same period -- the early Jurassic -- in Connecticut and Massachusetts,but very little about footprints in the Navajo sandstone in the southwest.
"The trackway was laid down at the base of the orange Navajo sandstoneat a time when that area was two or three days walk -- for a dinosaur -- fromthe shoreline to the west," said Cuffey. "The area was a desert created bywind-blown sand coming from the east, although there would have been a few smallponds of water between dunes for drinking."
The Penn State scientist and his students compared the Pipe Springfootprints with outlines of other dinosaur footprints found elsewhere to try toidentify the animal that made them. He is fairly certain that they were made bya theropod, and most probably the kind known as Eubrontes.
"Because of the 8-foot length of the stride, this was a medium tolarge dinosaur," said Cuffey.
The theropods include both the enormous Tyrannosaurus Rex and the nowfamous velociraptors as well as some smaller scavenger dinosaurs and medium-sizecarnivores.
"One thing we did find out, was that the nice, clear outline drawings ofdinosaur prints are rather difficult to match to the ragged and somewhat blurrededges of the actual footprints," said Cuffey. "A precise identification at thistime is therefore elusive."
While the exact pedigree of the dinosaur tracks is still unknown, theyshould be available for viewing for quite a while. Currently, the Pipe SpringNational Monument personnel go up every few months to sweep away the fine gravelthat periodically blows across and obscures the prints. Cuffey has suggested tothe National Parks Service that a fence or railing be installed so that thefootprints can be viewed, but no one can inadvertently step on or damage them.
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